The GP was acquitted of murdering three patients with painkillers in 2005. Sixteen other cases remain in the hands of Durham Coroner Andrew Tweddle.

In December last year, the 71-year-old GP, who used to practise in Newton Aycliffe before retiring to Penmaenmawr, North Wales, was unanimously cleared by a jury of killing Frank Moss, 59, and Harry Gittins and Stanley Weldon, both 74, by injecting them with massive overdoses of morphine, after a six week trial.

Dr Martin remains suspended by the General Medical Council after the High Court extended by a further two months an interim order imposed by the medical watchdogs 18 months ago.